Systems and methods for a twisted pair transceiver with correlation detection

ABSTRACT

The systems and methods for a twisted pair transceiver with correlation detection includes a transceiver system operating on a cable. The transceiver system includes a receiver to obtain one or more data samples related to one or more encoded data symbols. The transceiver system further includes a first correlation filter to generate a first correlation output based on the one or more data samples, and a second correlation filter to generate a second correlation output based on the one or more data samples. The transceiver system further includes a detector. The detector compares the first correlation output with the second correlation output, generates an output data bit based on a comparison result, and sends the output data bit for data decoding.

CROSS-REFERENCE TO RELATED APPLICATION

This disclosure claims the benefit of U.S. Provisional PatentApplication No. 62/066,511, filed Oct. 21, 2014, which is herebyincorporated by reference herein in its entirety.

FIELD OF USE

This disclosure relates to a physical transceiver that operates on asingle twisted wire pair cable in a data transmission system; forexample, a local area network (LAN) implementing the IEEE 802.3(Ethernet) standard.

BACKGROUND OF THE DISCLOSURE

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of theinventors hereof, to the extent the work is described in this backgroundsection, as well as aspects of the description that may not otherwisequalify as prior art at the time of filing, are neither expressly norimpliedly admitted to be prior art against the present disclosure.

Physical transceivers that operate on a single twisted wire pair cableis a new application of LANs in the IEEE 802.3 (Ethernet) standard. Thesingle pair cable conveys signals from one transceiver to another via adual duplex channel. The IEEE 802.3 (Ethernet) Working Group has twoactive task forces in this area addressing 1 Gigabit and 100 Megabitsover a single twisted pair cable, i.e., 1000BASE-T1 and 100BASE-T1. As atransceiver can operate at multiple rates, two devices connected by acable can negotiate a commonly supported rate for both devices tooperate on.

Transceiver performance in a single twisted pair application can beimpaired by multiple sources of degradation. First the single twistedpair may be used to convey a voltage across the differential pairs alongthe length of the cable, e.g., the power over differential line (PoDL).The PoDL system requires a scheme to block the direct current (DC)voltage source from the transceiver. PoDL can also introduce significantnoise at low frequencies into the transmission system that can degradetransceiver performance. A high pass network or isolation device such ascapacitors or a magnetic transformer can be used to isolate thetransceiver from the DC voltage supplied to the differential wire pair.The isolation device may attenuate low frequency signals between thetransceiver and the differential wire pair. An example can be a firstorder high pass filter (HPF) at the cutoff frequency of 10 MHz. In asystem using PoDL with the 10 MHz HPF, the communication channel is nolonger suitable to implement typical baseband line codes such asNon-Return to Zero (NRZ) or IEEE 802.3 Clause 73 differential Manchesterencoding (DME) with a conventional receiver architecture, becausesignificant low frequency energy can be lost. Data recovery can thus bedifficult and system bit error performance is degraded.

Second, the system can be impaired by multiple broadband noise sourcessuch as thermal noise, which is typically modelled as additive whiteGaussian noise (AWGN).

Third, the system can be impaired by radio frequency narrow bandinterferers (NBI), which can couple onto the twisted pair and appear asan undesired signal at the receiver in addition to the desired signaland AWGN. The NBI is typically modeled as a sine wave. The levels of NBIin the single twisted pair transceiver application can be significant,relative to the transmit signal of the transceiver. For example, a NBIsignal of 200 mV can occur to a 1V nominal transmit level.

Fourth, the twisted pair cable itself may attenuate higher frequenciesand distort the transmitted signal introducing inter-symbol interference(ISI) at the receiving transceiver.

SUMMARY

The systems and methods for a twisted pair transceiver with correlationdetection include a method for pre-processing signals at a transceiver.The method includes obtaining one or more data samples related to one ormore encoded data symbols. The method further includes generating, via afirst correlation filter, a first correlation output based on the one ormore data samples, and generating, via a second correlation filter, asecond correlation output based on the one or more data samples. Themethod further includes comparing the first correlation output with thesecond correlation output. The method further includes generating anoutput data bit based on a comparison result, and sending the outputdata bit for data decoding.

In some implementations, the one or more data samples are received froma single twisted pair cable at the single twisted pair transceiver.

In some implementations, the one or more encoded data symbols includedifferential Manchester encoded symbols.

In some implementations, each of the one or more encoded data symbolsincludes a symbol period that has a clock transition spacing period anda data transition spacing period.

In some implementations, the first correlation filter or the secondcorrelation filter has a number of coefficients that match a totalnumber of the one or more data samples.

In some implementations, the first correlation filter has a first set ofcoefficients that are pre-defined to evaluate whether the one or moredata samples corresponds to an input data bit of 0.

In some implementations, the second correlation filter has a second setof coefficients that are pre-defined to evaluate whether the one or moredata samples correspond to an input data bit of 1.

In some implementations, the comparing includes comparing a firstabsolute value of the first correlation output with a second absolutevalue of the second correlation output. The output data bit isdetermined to be 1 if the second absolute value of the secondcorrelation output is greater than the first absolute value of the firstcorrelation output. Or the output data bit is determined to be 0 if thesecond absolute value of the second correlation output is no greaterthan the first absolute value of the first correlation output.

In some implementations, the comparing is performed at a dual set offilters for both positive and negative polarities of a first value ofthe first correlation output and a second value of the secondcorrelation output.

In some implementations, the one or more encoded data symbols aretransmitted at a baud rate that is compatible with two or moretransmission formats.

Some embodiments described herein include a transceiver system operatingon a cable. The transceiver system includes a receiver to obtain one ormore data samples related to one or more encoded data symbols. Thetransceiver system further includes a first correlation filter togenerate a first correlation output based on the one or more datasamples, and a second correlation filter to generate a secondcorrelation output based on the one or more data samples. Thetransceiver system further includes a detector. The detector comparesthe first correlation output with the second correlation output,generates an output data bit based on a comparison result, and sends theoutput data bit for data decoding.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the disclosure, its nature and various advantageswill be apparent upon consideration of the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout, and inwhich:

FIG. 1 provides a block diagram illustrating a communication system 100including physical transceivers that operate on a single twisted wirepair cable, in accordance with embodiments of this disclosure.

FIG. 2 provides an example diagram illustrating differential Manchesterencoding (DME) used in the IEEE 802.3 Ethernet standard, in accordancewith embodiments of this disclosure.

FIG. 3 provides an example diagram illustrating aspects of a half-duplexauto-negotiation scheme for a single twisted pair transceiverapplication, in accordance with embodiments of this disclosure.

FIG. 4 provides an example block diagram illustrating example structuresof a correlation detector 400 (e.g., similar to 105, 114 at FIG. 1) atthe physical transceiver (e.g., 104, 113 at FIG. 1) to improvetransmission performance, in accordance with embodiments of thisdisclosure.

FIG. 5 provides an example logic flow diagram illustrating aspects of aphysical transceiver operating a correlation detector to make a bitdecision, in accordance with embodiments of this disclosure.

DETAILED DESCRIPTION

This disclosure describes methods and systems for a physical transceiverthat operates on a single twisted wire pair cable in a data transmissionsystem; for example, a LAN implementing the IEEE 802.3 (Ethernet)standard. According to this disclosure, data samples obtained at atransceiver can be processed with a correlation detector before beingdecoded at a decoder. In this way, the effects from channel noise and/orinter-symbol interference (ISI) may be reduced and thus data performancecan be improved.

FIG. 1 provides a block diagram illustrating a communication system 100that includes physical transceivers that operate on a single twistedwire pair cable. A communication device A 101 can send and/or receivedata bits to a communication device B 111 via a communication channel,e.g., a single twisted wire pair cable 122. Each of the devices 101 and111 is a physical layer transceiver to send or receive signals from thecable 122.

When device A 101 sends a data packet to device B 111, the data packetmay be encoded by a line code mapper 103, and then processed at transmitprocessing block 102 to do waveform shaping and spectrum control taskssuch as digital filtering, digital to analog conversion (DAC), analogfiltering, and/or the like. In this example, the differential Manchesterencoding (DME) can be employed by the line code mapper 103, which is atype of line code specified in IEEE 802.3 clause 73 used to convey dataacross the link. The coupling network 106 will provide interface fortransmitting at transmitter 102, and receiving at receiver 104 to singletwisted pair cable 122. Device B 111, as a receiver of the data, maycorrespondingly include a coupling network 116 to interface with areceiver processing block 115, and a transmitter processing block 112.The transmitter processing block 112 is connected to a line code mapper113, which is similar to 103 in device A 101. The receiver processingblock 115 is connected to a correlation detector block 114 to processthe received data from cable 122. The receiver block 115 may performanalog anti-alias filtering, and analog to digital conversion (ADC),and/or the like. Various factors can affect the decoding performance ofthe communication system 100. For example, the channel cable 122 may beaffected by additive white Gaussian noise 120 (AWGN), radio frequencynarrow band interferences 121 (NBI), and/or the like. The datatransmission may also be affected by intersymbol interference (ISI)which may be characterized by a transfer function H(s) 122.

An example DME receiver (e.g., the physical transceiver 111) may rely ona baseband response of the communications channel 122 and sufficientbandwidth that a Non-Return to Zero (NRZ) two-level detector may be usedto detect and decode the DME symbols. The DME receiver may compare thesignal level in the middle of the clock transition spacing period to thesignal level in the middle of the data transition spacing period. If thelevels are different, then a data transition has occurred indicatingthat the data bit is 1.

In a system using power over differential line (PoDL) with 10 MHz HPF,the channel H(s) 122 is no longer baseband and such DME receiver may notreliably decode the data. A correlation detector 105 or 114 can beemployed to improve data performance. The correlation detector 105 or114 can process the received data signals from the cable channel 122,and generate the optimal output data bit estimate. The correlationdetector 105 correlates multiple data samples of one or more DME symbolsto reduce negative effects of channel noise and interferences, e.g.,AWGN 120, NBI 121, ISI, as further illustrated in FIGS. 4-5.

FIG. 2 provides an example diagram illustrating differential Manchesterencoding (DME) used in the IEEE 802.3 Ethernet standard. DME is a typeof line code specified in IEEE 802.3 clause 73 used to convey dataacross the link, which can be implemented at the line code mapper 103 inFIG. 1.

The DME code may start with a clock transition spacing period 201 with alength of T1, which can be 30 nanoseconds long. Each DME symbol period202 having a length of T2=60 nanoseconds consists of a clock transitionspacing period (with a length of T1=30 nanoseconds) followed by a bittransition spacing period 203 (with a length of T1=30 nanoseconds).

The clock transition spacing period 201 begins when the transmitter(e.g., see the device A 101 in FIG. 1) changes to the opposite of theprior state, causing a high-to-low or low-to-high transition on thetransmitted signal (e.g., the DME code). For example, after the firstclock transition spacing period, if the data bit to be transmitted is“1” at 205, the transmitter may change to the opposite of the priorstate, causing a high-to-low or low-to-high transition on thetransmitted signal, e.g., see 205-208. If the data bit to be transmittedis “0,” there is no change in the transmit signal, e.g., see 211-213.After a spacing period of T1, the next clock transition is sent.

Alternative implementations of DME can include using a data transitionon the transmitted signal when the data bit is “0” and no transitionwhen the data bit is “1.”

FIG. 3 provides an example diagram illustrating aspects of a half-duplexauto-negotiation scheme for a single twisted pair transceiverapplication. Further discussion on the auto-negotiation scheme can befound in commonly-owned, co-pending U.S. patent application Ser. No.13/350,969, which is hereby expressly incorporated by reference in itsentirety.

The negotiation protocol and state machine defined in 802.3 Clause 73can be implemented on baseband Non-Return-to-Zero (NRZ) serial links.The serial links use separate transmit and receive paths in ahalf-duplex negotiation scheme for dual-duplex transceivers. As shown inFIG. 3, the DME symbol period 302 is indicated by T2. Each symbol periodcontains two half-symbols representing data and clock, respectively, andmay be transmitted as a combination of high/high, high/low, low/high orlow/low depending upon the prior symbol and the current data bit. Forexample, a transition in the middle of the symbol indicates the data bitis 1, as illustrated in the example at FIG. 2.

The link code word can include a set of data bits contained within anoverall auto-negotiation page 303. The start of the page 303 a canimmediately follow a start delimiter 305, which is inserted to mark thestart of the page followed by DME coded data. The auto-negotiation page303 ends with an end delimiter 306 to mark the end of the page 303 b.

In the example shown at FIG. 3, an auto-negotiation page carries a48-bit link code word. The page can consist of 158 (e.g., 24+128+6)evenly spaced transition positions that contain a starting Manchesterviolation delimiter, the 48-bit link code word, a 16-bit cyclicredundancy check (CRC), and an ending Manchester violation delimiter.Odd-numbered transition positions represent clock information, andeven-numbered transition positions represent data information. The pageis alternately transmitted between the two devices with quiet periods307 a-b separating the pages.

For example, the first 24 transition positions can contain the startingManchester violation delimiter, which marks the beginning of the page.The starting Manchester violation contains a transition from quiet toactive at position 1, followed by transitions at positions 4, 7, 10, 13,16, 19, and 22, and no transitions at the remaining positions.

The last six transition positions contain the ending Manchesterviolation delimiter, which marks the end of the page. The endingManchester violation contains transitions at positions 153 and 156 andno transitions at the remaining positions. Position 159 contains atransition from active to quiet. The starting and ending Manchesterviolation delimiter may be the only place where three intervals occurbetween transitions. This allows the receiver to obtain pagesynchronization.

One issue to consider when defining an auto-negotiation mechanism isthat the transmit signaling and receiver implementation should not addunnecessary complexity to the lower speed device. In this case, the100BASE-T1 operates at a rate of 66⅔ million baud (Mbaud) with atransmitter and receiver operating at bandwidths around 33⅓ MHz. A1000BASE-T1 operates at a rate of 750 Mbaud with a transmitter andreceiver operating at bandwidths around 375 MHz.

To avoid hardware overhead, an auto-negotiation between a device thatsupports only 100BASE-T1 and a device that supports 1000BASE-T1 and100BASE-T1 should not require the 100BASE-T1 device to operate atbandwidths higher than 33⅓ MHz or baud rates higher than 66⅔ Mbaud.

Similarly, the auto-negotiation scheme should be compatible with thetransmitters designed for 100BASE-T1. To avoid electromagnetic radiationcompliance issues, the auto-negotiation signaling should comply with thetransmit power spectral density for 100BASE-T1.

The selection of auto-negotiation signaling should also be compatiblewith a transmitter and/or a receiver designed for 1000BASE-T1 operation.A device that supports only 1000BASE-T1 should not require addedcomplexity to transmit and receive the auto-negotiation signaling.

The compatibility and complexity issue may be addressed by selecting aDME baud rate that is compatible with the baud rates of both 100BASE-T1(66⅔Mbaud) and 1000BASE-T1 (750 Mbaud). Selecting a baud rate that is acommon factor of 66⅔Mbaud and 750 Mbaud allows both types of devices totransmit and receive DME symbols with little or no added complexityrequired.

For example, when a baud rate of 16⅔ Mbaud is selected, the baud rate isequal to ¼ of the 66⅔ Mbaud rate for 100BASE-T1 and 1/45 of the 750Mbaud rate for 1000BASE-T1. A 100BASE-T1 device can transmit the DMEsymbol using four samples at 66⅔ Mbaud. A 1000BASE-T1 device cantransmit the DME symbol using 45 samples at 750 Mbaud. Other commonfactors may be selected to define the baud rate. However, selecting acommon factor at baud rates lower than 16⅔ Mbaud may degrade theperformance of DME detection in a system using PoDL with 10 MHz HPF.

In the above example, implementing a 1000BASE-T1 device may use analogor digital filtering to shape the transmit signal, e.g. Tx block 102 indevice 101. The signal may be shaped to conform to 100BASE-T1transmitter specifications or to filter out frequencies beyond the DMEsignaling bandwidth.

FIG. 4 provides an example block diagram illustrating example structuresof a correlation detector 400 (e.g., similar to 105, 115 at FIG. 1) atthe physical transceiver (e.g., 101, 111 at FIG. 1) to improvetransmission performance.

The physical transceiver (e.g., 101, 111 at FIG. 1) can employ acorrelation detector 400 that operates on two or more samples 401-402per DME symbol, and operates on one or more DME symbols per bitdecision. For example, when there are two equally spaced samples persymbol, e.g., one during the clock transition spacing period and oneduring data transition spacing period, the two samples 401 are processedby two two-tap correlation filters 403-404 with coefficients selected tomatch the response of the DME symbol for cases when the data bit is 0or 1. These coefficients respectively are [z₁, z₂] and [o₁, o₂]. As anexample, the coefficients may be selected from the set [+1, 0, −1], butare not limited to these choices.

Consider an example DME symbol where the data bit=1 and the prior signallevel was +1. The DME symbol begins with a clock transition periodhaving a high-to-low transition, e.g., +1 to −1, followed by a datatransition period low to high, e.g., −1 to +1. If the two receivedsamples for this DME symbol are y₁ and y₂, the correlation filteroutputs 405-406 can be represented as z_(out)=z₁×y₁+z₂×Y₂ ando_(out)=o₁×y₁+o₂×y₂. The coefficients may be set to z₁=+1, z₂=+1, o₁=−1,o₂=+1.

A detector 410 then compares the absolute values of z_(out) 405 ando_(out) 406. If the absolute value of o_(out) is greater than theabsolute value of z_(out), then the data bit is decided to be a “1.”Otherwise, the data bit is decided to be a “0.” For example, if thereceived samples y₁=−0.5, y₂=+0.5, z_(out)=0, o_(out)=1. The detectoroutput is 1, e.g., the data bit is decided to be “1.”

Consider a case when the transmitted data bit is a “0.” The DME symbolmay begin with a clock transition period high to low, e.g., +1 to −1,followed by a data transition period (with no transition), e.g., −1 to−1. For received samples y₁=−0.5, y₂=−0.5, z_(out)=−1, o_(out)=0. Thedetector output is determined to be 0, e.g., the data bit is decided tobe “0.”

The correlation detector may be expanded to process multiple samples(e.g., a number N greater than 2) per DME symbol. For example, if N=5,the coefficients may be set to z=[+1, +1, +1, +1, +1] and o=[−1, −1, 0,+1, +1]. A “0” coefficient is used where a transition occurs within thesymbol. Similarly, the detector compares the absolute values of z_(out)and o_(out). If the absolute value of o_(out) is greater than theabsolute value of z_(out), then the data bit is decided to be a “1.” Forexample, when the transmitted data bit is a 1, and the received 5samples are y=[−0.4, −0.6, 0, 0.4, 0.6], then z_(out)=0, o_(out)=2. Thedetector output is 1. In another example, when the transmitted data bitis a 0, and the received data samples are y=[−0.4, −0.6, −0.8, −0.6,−0.4], then z_(out)=−2.8, o_(out)=0. The detector output is 0.

In one implementation, for the DME system with baud rate of 16⅔ Mbaud, a1000BASE-T1 device may be designed to sample the DME symbols at the rateof 750 MHz resulting 45 samples per DME symbol. The device may also bedesigned to sample the DME symbols at a sampling rate of 750 MHz dividedby a factor of N greater than 1, such as 750/15, 750/9, or 750/5 MHz,and/or the like.

When the sampling rate is 750 MHz (or 750/15, 750/9, or 750/5 MHzdiscussed above), the correlation filter may use 45 received samples andthe respective 45 coefficients per symbol, or a decimated number ofsamples and coefficients per symbol selected from a factor of 45, suchas 15, 9, or 5.

Detector performance may be improved by expanding the correlation filterto process more than one DME symbol. The correlation detector mayprocess 1 and ½ DME symbols. For the case N=6, then z and o have 9coefficients according to the 9 samples for the 1½ DME symbols. Thecoefficients may be set to z=[+1, +1, +1, +1, +1, +1, −1, −1, −1] ando=[−1, −1, −1, +1, +1, +1, −1, −1, −1]. In this example there are twoDME symbols where the data bits=1, followed by 0 and the prior signallevel was +1. The first DME symbol begins with a clock transition periodfrom +1 to −1, followed by a data transition period from −1 to +1. Thesecond DME symbol begins with a clock transition period +1 to −1,followed by a data transition period (with no transition) −1 to −1. Forthe first symbol detection the first 9 samples are used. If y=[−0.4,−0.5, −0.6, 0.4, 0.5, 0.6, −0.4, −0.5, −0.6], then z_(out)=−1.5,o_(out)=4.5. Thus the detector output is 1.

In another example, if there are two DME symbols where the data bits=0,followed by 1, and the prior signal level was +1, the first DME symbolbegins with a clock transition period +1 to −1 followed by a datatransition period (with no transition) −1 to −1. The second DME symbolbegins with a clock transition period −1 to +1, followed by a datatransition period +1 to −1. If y=[−0.4, −0.5, −0.6, −0.7, −0.8, −0.9,+0.4, +0.5, +0.6], then z_(out)=−5.4, o_(out)=−2.4. The detector outputis thus 0.

The detector performance may be further improved by selectingcorrelation filters designed to improve performance in the presence ofnoise or narrowband interference. For example, a correlation detectorthat processes 1 and ½ DME symbols and N=45 samples per symbol can beconstructed to counter narrow band interference.

In this example the correlation detector processes 1 and ½ DME symbolsand N=45 samples per symbol. The following coefficients can be definedas:P=22 coefficients of +1, e.g. [+1,+1, . . . ,+1,+1]M=22 coefficients of −1, e.g. [−1,−1, . . . ,−1,−1]Z=22 coefficients of 0, e.g. [0,0, . . . ,0,0]Then the coefficients may be set to z_(ppm)=[P, 1, P, M] for a total of22+1+22+22=67 coefficients, indicating the bit is a 0; and o_(ZPM)=[Z,0, P, M] for a total of 22+1+22+22=67 coefficients, indicating the bitis a 1.

In this example, assuming that there are two DME symbols where the databits=1, followed by 0 and the prior signal level was +1. Thus the firstDME symbol begins with a clock transition period +1 to −1, followed by adata transition period −1 to +1. The second DME symbol begins with aclock transition period +1 to −1, followed by a data transition period(with no transition) −1 to −1. For the first symbol detection, the first67 samples are used, e.g., y=[M, 0, P, M] for a total of 22+1+22+22=67samples. Then z_(out)=z_(PPM)×y=22, o_(out)=o_(ZPM)×y=44, where ‘x’stands for vector inner product of two vectors. The detector then checksfor the larger of the absolute value of the two correlation outputs,e.g., in this case |o_(out)|>|z_(out)| and the detector output is 1,where |.| stands for absolute operator.

In the same example, assuming two DME symbols but the data bits=0,followed by 1, and the prior signal level was +1. The first DME symbolbegins with a clock transition period +1 to −1 followed by a datatransition period (with no transition) −1 to −1. The second DME symbolbegins with a clock transition period −1 to +1, followed by a datatransition period +1 to −1. Consider y=[M, −1, M, P] for a total of22+1+22+22=67 samples, then z_(out)=z_(PPM)×y=−67,o_(out)=o_(ZPM)×y=−44. Then in this case |z_(out)|>|o_(out)|, and thedetector output is 0.

The DME correlation detector may be further combined with a signalenergy detect scheme. The DME correlation detector may be held in adisabled or low power state, until the link partner begins transmittingand triggering the receiver energy-detect unit to enable the DMEcorrelation detector. In this way, power overhead of implementing theDME correlation detector at a transceiver can be reduced.

FIG. 5 provides an example logic flow diagram illustrating aspects of aphysical transceiver operating a correlation detector to make a bitdecision. At 501, the physical transceiver may receive data samples ofone or more DME symbols. For example, as discussed in connection withFIG. 4, a correlation detector at the physical transceiver may process anumber N data samples of a DME symbols, or multiple DME symbols. Thedata samples may then be passed on to a first correlation filter at 502,which may be used to evaluate whether the data bit is 0. For example,the first correlation filter may generate a first output, e.g., z_(out)405 in FIG. 4. At 503, the correlation detector may pass the datasamples to a second filter and generate a second output that mayevaluate whether the data bit is 1. For example, the second correlationfilter output may be similar to o_(out) 406 in FIG. 4. It is noted thatsteps 502 and 503 may be performed in parallel, or in any sequentialorder. The correlation detector may then compare the first output andthe second output at 504. If the absolute value of the second output isgreater than the absolute value of the first output, the detector mayoutput a 1 at 506. Otherwise, the detector may output a 0 at 507.

While various embodiments of the present disclosure have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the disclosure. It should beunderstood that various alternatives to the embodiments of thedisclosure described herein may be employed in practicing thedisclosure. It is intended that the following claims define the scope ofthe disclosure and that methods and structures within the scope of theseclaims and their equivalents be covered thereby.

The foregoing is merely illustrative of the principles of thisdisclosure, and various modifications can be made without departing fromthe scope of the present disclosure. The above-described embodiments ofthe present disclosure are presented for purposes of illustration andnot of limitation, and the present disclosure is limited only by theclaims that follow.

What is claimed is:
 1. A method for processing signals for data decodingat a transceiver, the method comprising: obtaining, at a transceiver,one or more data samples related to one or more encoded data symbols;generating, via a first correlation filter, a first correlation outputbased on the one or more data samples; generating, via a secondcorrelation filter, a second correlation output based on the one or moredata samples; comparing a first absolute value of the first correlationoutput with a second absolute value of the second correlation output;generating an output data bit of a first binary value when the secondabsolute value of the second correlation output is greater than thefirst absolute value of the first correlation output; generating theoutput data bit of a second binary value when the second absolute valueof the second correlation output is no greater than the first absolutevalue of the first correlation output; and sending the output data bitfor data decoding.
 2. The method of claim 1, wherein the one or moredata samples are received from a single twisted pair cable at a singletwisted pair transceiver.
 3. The method of claim 1, wherein the one ormore encoded data symbols include differential Manchester encodedsymbols.
 4. The method of claim 1, wherein each of the one or moreencoded data symbols includes a symbol period that has a clocktransition spacing period and a data transition spacing period.
 5. Themethod of claim 1, wherein the first correlation filter or the secondcorrelation filter has a number of coefficients that match a totalnumber of the one or more data samples.
 6. The method of claim 1,wherein the first correlation filter has a first set of coefficientsthat are pre-defined to evaluate whether the one or more data samplescorresponds to an input data bit of
 0. 7. The method of claim 6, whereinthe second correlation filter has a second set of coefficients that arepre-defined to evaluate whether the one or more data samples correspondto an input data bit of
 1. 8. The method of claim 7, wherein the firstbinary value is 1 and the second binary value is
 0. 9. The method ofclaim 1, wherein the comparing is performed at a dual set of filters forboth positive and negative polarities of a first value of the firstcorrelation output and a second value of the second correlation output.10. The method of claim 1, wherein the one or more encoded data symbolsare transmitted at a baud rate that is compatible with two or moretransmission formats.
 11. A transceiver system operating on a cable, thetransceiver system comprising: a receiver to obtain one or more datasamples related to one or more encoded data symbols; a first correlationfilter to generate a first correlation output based on the one or moredata samples; a second correlation filter to generate a secondcorrelation output based on the one or more data samples; and a detectorto: compare a first absolute value of the first correlation output witha second absolute value of the second correlation output, generate anoutput data bit of a first binary value when the second absolute valueof the second correlation output is greater than the first absolutevalue of the first correlation output, generate the output data bit of asecond binary value when the second absolute value of the secondcorrelation output is no greater than the first absolute value of thefirst correlation output, and send the output data bit for datadecoding.
 12. The system of claim 11, wherein the one or more datasamples are received from a single twisted pair cable at a singletwisted pair transceiver of the transceiver system.
 13. The system ofclaim 11, wherein the one or more encoded data symbols includedifferential Manchester encoded symbols.
 14. The system of claim 11,wherein each of the one or more encoded data symbols includes a symbolperiod that has a clock transition spacing period and a data transitionspacing period.
 15. The system of claim 11, wherein the firstcorrelation filter or the second correlation filter has a number ofcoefficients that match a total number of the one or more data samples.16. The system of claim 11, wherein the first correlation filter has afirst set of coefficients that are pre-defined to evaluate whether theone or more data samples correspond to an input data bit of
 0. 17. Thesystem of claim 16, wherein the second correlation filter has a secondset of coefficients that are pre-defined to evaluate whether the one ormore data samples correspond to an input data bit of
 1. 18. The systemof claim 17, wherein the first binary value is 1 and the second binaryvalue is
 0. 19. The system of claim 1, wherein the detector comprises adual set of filters for both positive and negative polarities of a firstvalue of the first correlation output and a second value of the secondcorrelation output.
 20. The system of claim 11, wherein the one or moreencoded data symbols are transmitted at a baud rate that is compatiblewith at least two transmission formats.